Core B of the PPG provides important support for all projects in standardized cell staining methods for flow cytometry and confocal microscopy, coordinates in vivo animal imaging, develops new imaging methods, and novel protein "foot printing" mass spectrometry methods. The new powerful protein foot-printing technology added to Core B services provides detailed information on protein-nucleic acid and proteinprotein interactions. The Imaging-Protein Core will provide common resources with quality assurance to the Five projects in the PPG. Multiuser instrumentation including the Leica Confocal Microscope and the MS in vivo Imaging System are used in a cost effective manner by trained technicians. Confocal imaging is an essential form of analysis for several key projects in the PPG. Live animal imaging using the MS instrumentation is rapidly becoming the standard for in vivo longitudinal Veal time' analysis of tumor distribution and virus expression and is essential for several of the proposed work in the competitive renewal. The AXIMA-CFR (MALDI-TOF) mass spectrometry is a key instrument to measure protein-protein, protein nucleic acid and protein-inhibitor, and has been added as a Core B service. Core B is within an outstanding environment and has documented interactions with all projects including numerous scientific publications. The Specific Aims of the Imaging-Protein Core B include: 1) To provide a standardized cell staining service of samples that will be analyzed by either confocal imaging through the PPG Imaging Core, or flow cytometry through the Analytical Cytometry Laboratory Shared Service of the Comprehensive Cancer Center, 2) To conduct standardized studies that makes use of Confocal Microscopy imaging for the quantitative analysis of virus and cell protein distribution and subcellular localization. To provide training and other techniques to the PPG user group, 3) To coordinate access to the MS Imaging System and provide training to the PPG user group, 4) To develop novel applications of the imaging instrumentation that will enhance the PPG directed research and lead more refined image analysis, 5) To employ the mass spectrometry (AXIMA-CFR MALDITOF) based protein foot printing technology for detailed characterization of protein-nucleic acid and proteinprotein interactions.